Experimental Study On The Shera Capacity Of Reinforced Concrete Beam With Partial Length Corrosion

Corrosion of reinforcing bar is one of important factors that affect the durabilityof reinforced concrete (RC) structures. At present, most research work on the flexuralcarrying capacity of corroded RC members has been carried out while little researchwork on the shear carrying capacity of corroded RC members has been done. Amongthe above mentioned research work, the assumption that the whole longitudinal tensilebars were corroded was mostly used. However, the corrosion of the longitudinaltensile bars may occur only within partial length of the elements. Althoughexperimental tests on the shear carrying capacity of RC beam with partial length werecarried out, the longitudinal tensile bars were exposed or complete loss of bondbetween the steel and concrete was presented. This is not the actual situation in theexisted RC structures.Considering the limited research works on the shear capacity of corrosiondamaged RC beams and only partial length of the beam was corroded in the existedRC elements, fourteen RC test specimens were designed and test study on shearbehaviour of the RC beams was carried out, where two noncorroded RC beams, fourRC beams with partially unbonded length and eight RC beams with partially corrodedlength located in one shear span were designed. The influence of the partiallyunbonded and corroded length on the behaviour and load capacity of the beam wasstudied.From this experimental study, it is found that the mechanical behaviour of thenormal beam and beam with partial length is quite different. For beams with partiallyunbonded length, no inclined cracks were observed in the shear span with the partiallyunbonded length and a drastic change in failure mode was also presented resulting inhigh load capacity; while for beams with partially corroded length, although all thebeams failed in the corrosion damaged shear span, their failure modes became morebrittle with the increased corrosion levels in longer partial length resulting in low loadcapacity. For the high corrosion level of the longitudinal reinforcing bars combiningwith severe pitting corrosion and the sequential rupture of the stirrups within thedamaged length, reduction of the load capacity and brittle failure may occur. This isvery dangerous in the safety-related RC structures. In assessing the residual life spanand reliability of the in-service RC structures, it is of great importance to consider thesevere corrosion damage within certain length of the RC elements, especially whenthis certain length is located near the supports.Due to the lack of the research on the shear capacity and failure mode of the RCbeams with partial length corrosion within one shear span, this study of great importance and will help for the predicting of the residual life strength of existing RCbeams with partiallycorroded length.